3D thermal detection circuits and methods

Abstract

A three-dimensional integrated circuit includes a first layer including at least one sensing element configured to output at least one temperature-dependent voltage; and a second layer disposed vertically with respect to the first layer and coupled to the first layer by at least one via. The second layer includes: a compare circuit configured to generate at least one intermediate voltage in response to comparing the at least one temperature-dependent voltage to a feedback voltage; a control circuit configured to generate at least one control signal in response to the intermediate voltage; and a switching circuit configured to couple a capacitor coupled to a feedback node to one of a first voltage supply and a second voltage supply in response to the at least one control signal to generate an output signal that is based on a temperature sensed by the sensing element.

What is claimed is: 
     
       1. A three-dimensional integrated circuit, comprising:
 a first layer including at least one sensing element configured to output at least one temperature-dependent voltage; and 
 a second layer disposed vertically with respect to the first layer and coupled to the first layer by at least one via, the second layer comprising:
 a compare circuit configured to generate a first difference voltage and a second difference voltage in response to comparing the at least one temperature-dependent voltage to a feedback voltage; 
 a control circuit configured to generate a first control signal and a second control signal in response to the first and second difference voltages, respectively, wherein the control circuit comprises a first logic gate having a first input and a second logic gate having a second input, the first input configured to receive the first difference voltage and the second input configured to receive the second difference voltage; and 
 a switching circuit configured to selectively charge and discharge a capacitor using a first voltage supply and a second voltage supply, respectively, in response to the at least one control signal so as to generate an output signal that is based on a parameter sensed by the sensing element, wherein the at least one sensing element comprises: 
 a first switch coupled to a first node disposed between a power supply node and a first resistor, the first switch configured to couple the first node to a first input of compare circuit to generate the first difference voltage; and 
 a second switch coupled to a second node disposed between the first resistor and a second resistor, the second switch configured to couple the second node to a second input of the compare circuit to generate the second difference voltage. 
 
 
     
     
       2. The circuit of  claim 1 , further comprising a plurality of layers disposed vertically with respect to the first layer, each of the plurality of layers includes at least one respective sensing element configured to output at least one temperature-dependent voltage. 
     
     
       3. The circuit of  claim 1 , wherein the first and second resistors each have a resistance that is based on a temperature of the first and second resistors, respectively. 
     
     
       4. The circuit of  claim 1 , wherein the control circuit includes a latch configured to receive a pair of difference voltages from the compare circuit and to output the at least one control signal in response. 
     
     
       5. The circuit of  claim 4 , wherein the switching circuit comprises:
 a first transistor having a source coupled to the first power supply, a drain coupled to a feedback node, and a gate configured to receive a first control signal of the at least one control signal output from the control circuit; and 
 a second transistor having a source coupled to the second power supply, a drain coupled to the feedback node, and a gate configured to receive a second control signal of the at least one control signal output from the control circuit. 
 
     
     
       6. The circuit of  claim 1 , wherein the capacitor is a temperature insensitive capacitor. 
     
     
       7. The circuit of  claim 1 , wherein the first and second layers each include a respective substrate and interconnect, and wherein the at least one sensing element is disposed within the respective substrate or interconnect of the first layer. 
     
     
       8. A three-dimensional integrated circuit, comprising:
 a first layer including a first sensing element configured to output a first temperature-dependent voltage; 
 a second layer including a second sensing element configured to output a second temperature-dependent voltage; and 
 a third layer disposed vertically with respect to the first and second layers and coupled to the first and second layers by at least two through-substrate-vias (TSVs), the third layer including: 
 a compare circuit configured to generate a first difference voltage in response to comparing the first temperature-dependent voltage to a feedback voltage and generate a second difference voltage in response to comparing the second temperature-dependent voltage to the feedback voltage, wherein the compare circuit comprises a first comparator have a first input configured to receive the first temperature-dependent voltage and a second input configured to receive the feedback voltage and a second comparator having a third input configured to receive the second temperature-dependent voltage and a fourth input configured to receive the feedback voltage; 
 a control circuit configured to generate first and second control signals in response to the first and second difference voltages, respectively; and 
 a switching circuit configured to selectively charge and discharge a capacitor using a first voltage supply and a second voltage supply, respectively, in response to the two control signals so as to generate an output signal that is based on temperatures sensed by the first and second sensing elements. 
 
     
     
       9. The circuit of  claim 8 , wherein the first and second sensing elements each comprises at least one resistor having a resistance that is based on a temperature of the at least one resistor. 
     
     
       10. The circuit of  claim 8 , wherein the control circuit includes a latch configured to receive a pair of difference voltages from the compare circuit and to output the two control signals in response. 
     
     
       11. The circuit of  claim 10 , wherein the switching circuit comprises:
 a first transistor having a first source coupled to the first voltage supply, a first drain coupled to a feedback node, and a first gate configured to receive one of the two control signals output from the control circuit; and 
 a second transistor having a second source coupled to the second voltage supply, a second drain coupled to the feedback node, and a second gate configured to receive the other of the two control signals output from the control circuit. 
 
     
     
       12. The circuit of  claim 8 , wherein the capacitor is a temperature insensitive capacitor. 
     
     
       13. A method, comprising:
 sensing temperatures of first and second sensing elements and outputting first and second temperature-dependent voltages in response; 
 outputting first and second difference voltages based on comparing the first and second temperature-dependent voltages to a feedback voltage, respectively; 
 outputting first and second control signals in response to the first and second difference voltages, respectively; 
 selectively charging and discharging a capacitor using a first voltage source and a second voltage source in response to the first and second control signals, respectively; and 
 outputting a signal having a pulse-width that is based on the temperature of the first and second sensing elements. 
 
     
     
       14. The method of  claim 13 , wherein comparing the first and second temperature-dependent voltages to the feedback voltage comprises:
 coupling a first node between a power supply and a first resistor to a first input of a first comparator, a second input of the first comparator being configured to receive the feedback signal; and 
 coupling a second node between the first resistor and a second resistor to a third input of a second comparator, a fourth input of the second comparator being configured to receive the feedback signal. 
 
     
     
       15. The method of  claim 13 , wherein the first and second sensing elements are disposed on a first layer of a three-dimensional integrated circuit and is coupled to other circuitry disposed on a second layer of a three-dimensional integrated circuit by a via. 
     
     
       16. The method of  claim 13 , wherein selectively charging and discharging the capacitor includes coupling the capacitor to one of the first voltage source and the second voltage source.